Morgan Stanley, one of the world's biggest investment banks, has found itself advising opposite a publicity-shy boutique on one of the year's largest M&A transactions in Europe.

The US bank is working for Danish transport and energy company AP Møller-Mærsk on the $7.45bn sale of its oil and gas business to France's Total, which is being advised by Lambert Energy Advisory, a Mayfair-based energy-sector boutique, according to two sources familiar with the advisory line-up. Goldman Sachs is advising the Moller family holding company.